According to the most comprehensive survey of people affected by Hurricane Katrina, results of which are being presented to the US Senate, the percentage of pre-hurricane residents of the affected areas who have mental disorders has increased significantly compared to the situation five to eight months after the hurricane. These findings counter a more typical pattern from previous disasters where prevalence of mental disorders decreases as time passes.

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According to the most comprehensive survey of people affected by Hurricane Katrina, results of which are being presented today to the U.S. Senate Committee on Homeland Security and Government Affairs Ad Hoc Subcommittee on Disaster Recovery, the percentage of pre-hurricane residents of the affected areas in Alabama, Louisiana, and Mississippi who have mental disorders has increased significantly compared to the situation five to eight months after the hurricane. These findings counter a more typical pattern from previous disasters where prevalence of mental disorders decreases as time passes.

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These and other survey results come from follow-up interviews with the Hurricane Community Advisory Group, a statistically representative sample of hurricane survivors assembled to provide information in a series of ongoing tracking surveys about the pace of recovery efforts and the mental health effects of these efforts on hurricane survivors.

"It is important for mental health policy planners to have accurate information about the size of the problem they are trying to address among survivors of Hurricane Katrina," says Ronald Kessler, Professor of Health Care Policy at Harvard Medical School and director of the study. "Our tracking surveys are designed to provide that information."

Hurricane Katrina was the deadliest United States hurricane in seven decades, and the most expensive natural disaster in U.S. history. Over 500,000 people were evacuated, and nearly 90,000 square miles were declared a disaster area (roughly equal to the land mass of the United Kingdom). Although occurring over two years ago, infrastructure reconstruction efforts continue to lag, raising concerns about long-term mental health effects.

The Hurricane Katrina Community Advisory Group initiative was launched to provide an ongoing tracking survey of those effects. The data are designed to help support public health decisions.

The survey data presented in the report released today come from a follow-up survey from an original sample of 1,043 people who agreed to join the survey panel and to participate in repeated surveys over several years.

Overview of Initial Survey Published in August 2006

Seven percent of respondents reported experiencing an event that would be considered seriously traumatic (had to be rescued, any life-threatening experience, physical or sexual assault), and 18.7 percent reported that a traumatic event of this sort (including death) occurred to someone close to them.

The estimated prevalence of anxiety-mood disorders in the baseline survey was roughly twice as high as found three years earlier using the same measures in a survey of residents subsequently affected by Hurricane Katrina.

Socio-demographic variables were largely unrelated to these trends, suggesting that the short-term adverse mental health effects of Hurricane Katrina were equally distributed across broad segments of the population.

The prevalence of suicidality in the baseline survey was quite low, despite the high rates of anxiety and depression. This low prevalence of suicidality was traced to widespread feelings of optimism that the practical problems created by the hurricane would soon be resolved.

This optimism turned out to be unrealistic, raising the question of whether or not the slow pace of recovery increased the prevalence of suicidality. This possibility was investigated in the follow-up survey

Overview of Follow-Up Survey Results

The typical finding in post-disaster tracking surveys is that the prevalence of mental disorders significantly decreases with time, with up to half of post-disaster mental disorders typically resolving within a year and the vast majority within two years.

The follow-up survey found quite a different pattern after Hurricane Katrina: the number of people with any anxiety or mood disorder did not change significantly between the baseline survey and the follow-up survey. (If anything, the trend was upward from 30.7% to 33.9%.)

The estimated prevalence of serious mental illness, in comparison, was significantly higher in the follow-up survey than the baseline survey in the total sample (14.0% vs. 10.9%) as well as in the sub-sample of respondents who are not from the New Orleans Metropolitan Area (13.2% vs. 9.4%). This trend was not significant, in comparison, in the New Orleans Metro sub-sample (16.9% vs. 16.5%).

The estimated prevalence of PTSD roughly doubled in the follow-up survey compared to the baseline survey in the sub-sample exclusive of New Orleans Metro (20.0% vs. 11.8%), but did not change in the New Orleans Metro sub-sample (24.1% vs. 25.9%).

The prevalence of suicidality, finally, was significantly higher in the follow-up survey than the baseline survey both with regard to suicidal ideation (6.4% vs. 2.8%) and suicide plans (0.8% vs. 0.2%).

The suicidality trends, unlike those for anxiety-mood disorders and PTSD, were statistically significant and relatively comparable in magnitude in both the New Orleans Metro sub-sample and in the remainder of the sample.

The majority of respondents with baseline serious mental illness (SMI; 51.1%) continued to have serious mental illness at follow-up, while 30.8% improved (i.e., were classified as having less severe mental illness at follow-up) and only a relatively small minority (18.1%) recovered (i.e., no longer met criteria for an anxiety-mood disorders).

In the case of PTSD, 70.4% of baseline cases continued to have PTSD at follow-up, while an additional 10.3% were classified as having some other anxiety-mood disorder but not PTSD at follow-up, and only 19.3% recovered.

Persistence was somewhat lower for suicidal ideation (37.9%), but much higher for plans (69.8%). Improvement, in comparison, was comparatively high for suicidal ideation (49.9%), but not for suicide plans (16.0%). Recovery (i.e., no mental illness and no suicidality at follow-up), finally, was relatively uncommon for either suicidal ideation (12.2%) or plans (18.0%).

As noted above, researchers expected to find lower proportions of the population to have mental illness and suicidality this long after a disaster. Failing to find such a decrease, and instead discovering a number of increases, is an indication of the more severe adverse emotional effects of Hurricane Katrina than more typical disasters.

As in the baseline survey, socio-demographic variables were generally not significant predictors of trends in anxiety-mood disorders or suicidality in the two surveys, indicating that these adverse effects were widespread in the population.

The fact that hurricane-related stressors were still quite common in the population nearly two years after the hurricane, and that much of this could be attributed to these continuing stresses suggests that efforts to address the problem of increased mental illness and suicidality among Hurricane Katrina victims must confront continuing needs for practical and logistical assistance. This may be particularly challenging since many pre-hurricane residents of the affected areas are now living elsewhere in the country. Still, it is especially important to reach these geographically displaced people because of their comparatively high risk of serious mental illness.

The study is led by researchers from Harvard Medical School and is funded by the National Institute of Mental Health, FEMA, and the Office of the Assistant Secretary of the Department of Health and Human Services for Planning and Evaluation.

The detailed results of this report are in press in the journal Molecular Psychiatry.

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